Her first acting role was as Nicky in the BBC children's television series The Biz in 1995, appearing alongside Paul Nicholls. She subsequently appeared in several television series, including Peak Practice, Where the Heart Is, Casualty, Heartbeat, The Bill, Dalziel and Pascoe, Holby City, The Line of Beauty, Luther, Criminal Justice, Coronation Street, Sons and Lovers. She has also performed for Real Circumstance Theatre Company.
In 2001, she appeared in an all-star Family Fortunes: Heartbeat vs Peak Practice edition.
In 2015 Forsyth appeared as Terri Weedon in the BBC TV mini series The Casual Vacancy.
In 2016, she appeared as Annette in the second series of Happy Valley.
